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Engine-Codes – GMC – U1305 GMC

U1305 GMC Code - High Or Low Voltage On Class 2 Serial Data Circuit

Quick Answer

The U1305 GMC code indicates that there is a high or low voltage on the Class 2 serial data circuit in the vehicle. Common causes include Faulty wiring or connections in the Class 2 serial data circuit, Corrosion or damage to the connectors, Malfunctioning modules on the network. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
U1305 GMC indicates High Or Low Voltage On Class 2 Serial Data Circuit.
Common causes
Common causes include Faulty wiring or connections in the Class 2 serial data circuit, Corrosion or damage to the connectors, Malfunctioning modules on the network.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Sep 06, 2024
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Code U1305 GMC Description

The U1305 GMC code indicates that there is a high or low voltage on the Class 2 serial data circuit in the vehicle. The Class 2 serial data circuit is a communication network that allows various modules in the vehicle to communicate with each other. This network plays a crucial role in the operation of many systems in the vehicle, including the engine, transmission, anti-lock brake system, airbags, and more.

OBDII Code U1305 GMC - High Or Low Voltage On Class 2 Serial Data Circuit
U1305 GMC Code - High Or Low Voltage On Class 2 Serial Data Circuit

Common Causes of U1305 GMC

  1. Faulty wiring or connections in the Class 2 serial data circuit
  2. Corrosion or damage to the connectors
  3. Malfunctioning modules on the network
  4. Battery or alternator issues affecting voltage levels
  5. Water intrusion causing shorts in the circuit

Symptoms of U1305 GMC

  1. Erratic shifting
  2. Rough idling
  3. Stalling
  4. Dashboard warning lights illuminated
  5. Complete system failures

How to Fix U1305 GMC

  1. Begin by conducting a thorough inspection of the Class 2 serial data circuit, checking for any visible signs of damage, corrosion, or loose connections.
  2. Use a multimeter to test the voltage levels on the circuit and identify any discrepancies from the specified values.
  3. Address any wiring issues, repair or replace damaged connectors, and ensure all connections are secure.
  4. Test the modules on the network to determine if any are malfunctioning and replace as necessary.
  5. Clear the diagnostic trouble codes and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix U1305 GMC

The typical repair costs for addressing a high or low voltage on the Class 2 serial data circuit can vary depending on the specific underlying cause and the extent of the repairs needed. In general, the cost of parts and labor for this repair could range from $200 to $500. However, it's important to note that diagnostic time and labor rates at auto repair shops can vary significantly based on factors such as location, vehicle make and model, and engine type. It is advisable to contact local auto repair shops for a more accurate estimate based on the specific circumstances.

What does this mean?

Tech Notes for U1305 GMC

In most cases, the P1305 code is combined with other codes, fix other codes first.

Need more information about the U1305 GMC code?

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about U1305 GMC Code

1. What are the common symptoms of OBDII code U1305 in a GMC vehicle?

- Common symptoms include intermittent or total loss of communication with various control modules, erratic behavior of electrical systems, and warning lights on the dashboard.

2. What are the possible causes of OBDII code U1305 in a GMC vehicle?

- The code U1305 can be caused by issues such as loose or corroded wiring connections, a faulty Class 2 serial data circuit, a malfunctioning control module, or a damaged communication network.

3. How can I diagnose the OBDII code U1305 in my GMC vehicle?

- Diagnosis typically involves checking the wiring harness and connectors for signs of damage, testing the voltage on the Class 2 serial data circuit, and using a scan tool to communicate with the different control modules in the vehicle.

4. Can a DIY enthusiast repair the OBDII code U1305 issue in a GMC vehicle?

- Depending on the root cause, DIY enthusiasts may be able to address the issue by checking and repairing wiring connections, replacing damaged components, or resetting the communication network using a scan tool.

5. Is it safe to continue driving with the OBDII code U1305 present in a GMC vehicle?

- It is not recommended to continue driving with the U1305 code active, as it can lead to further electrical system malfunctions and potential safety hazards. It is best to address the issue promptly.

6. How much does it typically cost to repair the OBDII code U1305 in a GMC vehicle?

- The cost of repairing the U1305 code can vary depending on the underlying cause. Simple fixes like repairing wiring connections may be relatively inexpensive, while replacing a control module or fixing a complex communication network issue can be more costly.

7. Can extreme weather conditions affect the occurrence of OBDII code U1305 in a GMC vehicle?

- Yes, extreme weather conditions such as extreme heat or cold can sometimes exacerbate electrical issues leading to the U1305 code. It is important to keep the vehicle well maintained to prevent such issues.

8. Are there any preventive measures to avoid encountering the OBDII code U1305 in a GMC vehicle?

- Regular maintenance, including checking and cleaning wiring connections, ensuring proper grounding, and addressing any electrical issues promptly, can help prevent the occurrence of the U1305 code in a GMC vehicle.

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